Unaudited Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2020	Sep. 28, 2019	Sep. 26, 2020	Sep. 28, 2019
Revenue:
Revenue	$ 709,619	$ 732,082	$ 1,707,818	$ 1,665,612
Cost of revenue (excluding items shown separately below):
Net cost of revenue	469,004	482,979	1,165,317	1,155,476
General and administrative expenses	81,499	62,344	218,267	190,915
Depreciation, depletion, amortization and accretion	58,054	55,127	163,760	164,140
Transaction costs	445	751	1,517	1,449
Operating income	100,617	130,881	158,957	153,632
Interest expense	24,623	28,917	78,049	88,423
Loss on debt financings	4,064	0	4,064	14,565
Other income, net	(1,226)	(1,875)	(2,753)	(8,354)
Income from operations before taxes	73,156	103,839	79,597	58,998
Income tax (benefit) expense	(19,613)	45,602	(25,333)	34,272
Net income	92,769	58,237	104,930	24,726
Net income attributable to Summit Holdings	2,039	2,480	2,115	1,331
Net income (loss) attributable to Summit Inc/LLC	90,730	55,757	102,815	23,395
Summit Materials, LLC
Revenue:
Revenue	709,619	732,082	1,707,818	1,665,612
Cost of revenue (excluding items shown separately below):
Net cost of revenue	469,004	482,979	1,165,317	1,155,476
General and administrative expenses	81,499	62,344	218,267	190,915
Depreciation, depletion, amortization and accretion	58,054	55,127	163,760	164,140
Transaction costs	445	751	1,517	1,449
Operating income	100,617	130,881	158,957	153,632
Interest expense	24,561	28,800	77,807	88,020
Loss on debt financings	4,064	0	4,064	14,565
Other income, net	(1,226)	(1,875)	(2,753)	(8,354)
Income from operations before taxes	73,218	103,956	79,839	59,401
Income tax (benefit) expense	(5,106)	18,757	(4,877)	12,265
Net income	78,324	85,199	84,716	47,136
Net income (loss) attributable to Summit Inc/LLC	$ 78,324	$ 85,199	$ 84,716	$ 47,136
Common Class A
Earnings per share of Class A common stock:
Basic (usd per share)	$ 0.79	$ 0.50	$ 0.90	$ 0.21
Diluted (usd per share)	$ 0.79	$ 0.48	$ 0.90	$ 0.21
Weighted average shares of Class A common stock:
Basic (in shares)	114,116,564	112,179,137	113,943,292	112,020,275
Diluted (in shares)	114,472,171	115,505,122	114,457,276	112,497,610
Product
Revenue:
Revenue	$ 540,904	$ 554,721	$ 1,334,471	$ 1,293,999
Cost of revenue (excluding items shown separately below):
Net cost of revenue	331,853	338,119	857,912	846,702
Product | Summit Materials, LLC
Revenue:
Revenue	540,904	554,721	1,334,471	1,293,999
Cost of revenue (excluding items shown separately below):
Net cost of revenue	331,853	338,119	857,912	846,702
Service
Revenue:
Revenue	104,342	111,126	228,421	230,389
Cost of revenue (excluding items shown separately below):
Net cost of revenue	72,778	78,625	162,479	167,550
Service | Summit Materials, LLC
Revenue:
Revenue	104,342	111,126	228,421	230,389
Cost of revenue (excluding items shown separately below):
Net cost of revenue	72,778	78,625	162,479	167,550
Excluding delivery and subcontract revenue
Revenue:
Revenue	645,246	665,847	1,562,892	1,524,388
Cost of revenue (excluding items shown separately below):
Net cost of revenue	404,631	416,744	1,020,391	1,014,252
Excluding delivery and subcontract revenue | Summit Materials, LLC
Revenue:
Revenue	645,246	665,847	1,562,892	1,524,388
Cost of revenue (excluding items shown separately below):
Net cost of revenue	404,631	416,744	1,020,391	1,014,252
Delivery and subcontract revenue
Revenue:
Revenue	64,373	66,235	144,926	141,224
Cost of revenue (excluding items shown separately below):
Net cost of revenue	64,373	66,235	144,926	141,224
Delivery and subcontract revenue | Summit Materials, LLC
Revenue:
Revenue	64,373	66,235	144,926	141,224
Cost of revenue (excluding items shown separately below):
Net cost of revenue	$ 64,373	$ 66,235	$ 144,926	$ 141,224